Light waveguide communication cables are increasingly used in the modern network. Practical network planning must take into account that a message may need to travel over a number of different connected cables between the sender and receiver of a message. Cable or light waveguide fiber joints are often made using remateable connectors instead of permanent splices to give needed flexibility. Therefore, the efficient transfer of optical energy ultimately depends upon connection joints having the minimum optical loss. Accuracy is very important, and tolerances are often measured in terms of microns.
Reflections from connectors can degrade transmitter or receiver performance in high-speed and multichannel analog systems. To avoid an excessive link power penalty, the reflectance of individual connectors is sometimes specified.
Various grinding and polishing machines have been proposed to prepare connectors having a desired end face surface. Examples include Saito, et al, U. S. Pat. No. 5,007,209; Moulin, U. S. Pat. No. 4,905,415; Clark, U. S. Pat. No. 4,492,060; and Tamulevich, U. S. Pat. No. 4,272,926.
A separate, and much older, tradition of smoothing glass surfaces is flame polishing. Flame polishing of glassware in the chemical laboratory is quite old and well known. While satisfactory for ordinary polishing, it is believed that the typical Bunsen burner flame is insufficient to produce the precise tolerances needed in the practical production of optical connectors.
In yet another development, lasers have been used to form lens shapes on optical fiber ends by precise adjustment of focusing lenses interposed between the laser and the optical fiber.